fix GetResponse

void CModbus::GetResponse(byte* response, int nLength)
{
//There is a bug in .Net 2.0 DataReceived Event that prevents people
from using this
//event as an interrupt to handle data (it doesn't fire all of the
time).  Therefore
//we have to use the ReadByte command for a fixed length as it's been
shown to be reliable.

int index =0 ;
while(1)
{
if ( sp.ReadDataWaiting() == nLength)
{
sp.ReadData( response,nLength);
break;
}
//response[i] = (byte)(sp.ReadByte());
}

}